Various attempts have been made to treat cerebrovascular diseases with a drug. For example, cerebrovasodilators and cerebral metabolism activators are used. So far, however, there has been no drug which is very useful for the treatment of the cerebrovascular diseases. In particular, with respect to cerebrovascular dementia, mental dysfunction, etc. among various symptoms accompanying cerebrovascular diseases, no effective drug has yet been developed.
However, in recent years, a theory that an excitatory amino acid liberated after ischemia seriously participates in the death of nerve cells has attracted worldwide attention. This theory was substantiated by the facts that ischemia brings about liberation of a glutamate and the cell injury derived from ischemia is antagonized by a glutamate antagonist.
The present inventors have paid their attention to the neurotoxic activity of the above-described glutamate in starting the search for a new agent for treating cerebrovascular diseases, particularly an agent for improving a mental symptom accompanying the cerebrovascular diseases and have repeated studies on various compounds for a long period of time. As a result, we have found that a cyclic amine derivative which will be described hereinbelow exhibits an excellent activity on the suppression of glutamate liberation, which have led to the completion of the present invention.
Accordingly, an object of the present invention is to provide a cyclic amine derivative or pharmacologically acceptable salts thereof effective as an agent for improving mental symptoms accompanying cerebrovascular diseases, such as cerebral apoplexy, cerebral hemorrhage, cerebral infarction and cerebral arteriosclerosis, and polyinfarctive dementia, and a process for preparing said compound and pharmacologically acceptable salts thereof. Another object of the present invention is to provide a pharmaceutical comprising as an effective ingredient said compound or pharmacologically acceptable salts thereof.